Resource Leveling

 c.    Joan and Alcides are not fully dedicated to the project.  Joan is only available for 4 hours each day, and Alcides is available for 6 hours per day.  The original estimated duration (in 8-hour days) results in over-allocation of Joan and Alcides.  Prepare a resource-leveled project schedule in MS Excel.  How long will it take to complete the project in a resource-leveled environment? 

I need only question C and Mechanics.